In a Long Term Evolution (Long Term Evolution, “LTE” for short) system or a Long Term Evolution Advanced (Long Term Evolution Advanced, “LTE-A” for short) system, before a user equipment (User Equipment, “UE” for short) receives or sends service data, the UE needs to learn downlink control information (Downlink Control Information, “DCI” for short) configured by a Evolved NodeB (Evolved NodeB, “eNB” for short) for the UE. The DCI is carried by a physical downlink control channel (Physical Downlink Control Channel, “PDCCH” for short), and different DCI formats (DCI formats) may be used to indicate different transmission modes (Transmission Modes).
The LTE-A system has introduced a carrier aggregation (Carrier Aggregation, “CA” for short) technology, that is, the LTE-A system can concurrently receive or transmit a plurality of component carriers (Component Carriers, “CCs” for short). In the LTE-A system, DCI configured for each component carrier is independently encoded, that is, DCI configured for different component carriers is carried in different PDCCHs. In LTE-A release 10 (Release 10, “Rel-10” for short), each component carrier is backward compatible, that is, each component carrier can be accessed by UEs complying with LTE release 8/9 (Release 8/9, “Rel-8/9” for short), where such UEs are referred to as LTE Rel-8 UEs or LTE Rel-9 UEs. However, in LTE-A release 11 (Release 11, “Rel-11” for short) under discussion, one or more component carriers may be configured to be non-backward compatible. The non-backward compatible component carrier cannot be accessed by a UE complying with LTE release 8/9 and/or release 10.
To increase spectrum utilization, a cell-specific reference signal (Cell-specific Reference Signal, “CRS” for short) does not need to be configured on such non-backward compatible component carriers, that is, transmission of the CRS is not supported. The CRS does not need to be measured only in downlink transmission mode 9 of related downlink transmission modes. The CRS needs to be measured in other downlink transmission modes. Therefore, the non-backward compatible component carriers can support only downlink transmission mode 9.
However, downlink transmission mode 9 is not applicable to small-sized traffic (Small-Sized Traffic) and high-speed movement scenarios, that is, application scenarios of the non-backward compatible component carriers are limited, and therefore spectrum utilization is reduced. In addition, when a lot of non-backward compatible component carriers are configured, the system capacity may be decreased due to limitations on the application scenarios of the non-backward compatible component carriers.